Most indoor commercial spaces, such as offices, use incandescent, halogen, or fluorescent technology to provide light. These technologies can be used to illuminate many types of areas including employee workspaces, common use areas, and parking garages. However, the use of these technologies is increasingly counterproductive due to limitations such as energy inefficiency, high front end cost, maintenance costs, poor light quality, and negative environmental impact.
Commercial office space frequently utilizes fluorescent technology, which requires significant expenditures for the costs of material, maintenance, and energy consumption. This technology utilizes fluorescent lamps and ballasts attached to luminaires recessed into the ceiling plenum. Typically, fluorescent technology includes large and heavy structures, which require additional secondary support mechanisms for their installation. Replacement of fluorescent lights also generates additional cost due to mercury and other materials within the lamp. Consequently, fluorescent lights often must be disposed of as hazardous waste.
Fluorescent technology generally consumes high levels of energy and is a significant source of costs in operating a commercial office building. A portion of the energy consumed by fluorescent lamps is dissipated as heat, thus increasing the building's mechanical load. Costs associated with removal of the heat generated by fluorescent lamps include initial front end cost, such as upsizing the HVAC units, subsequent operational costs resulting from higher energy consumption, and increased maintenance costs. Although improvements in fluorescent technology such as the development of lower wattage lamps with improved electrodes and coatings as well as more efficient electronic ballasts have reduced, but not eliminated, the amount of heat dissipated by such systems, these improvements have not solved problems with visual comfort and energy inefficiency.
The lighting industry has addressed the problems of energy consumption and visual discomfort due to the fluorescent lighting glare in three ways. Replacement of fluorescent lamps with lower wattage lamps, removal of lamps in a process called de-tamping, and developing secondary optical reflectors to reduce glare. However, fluorescent lamps with series wired ballasts cannot function with fewer lamps than intended, making delamping infeasible which requires additional expenditures for retrofitting. Engineered reflective surfaces surrounding the lamp have been utilized to increase luminaire efficiency at the workplane and to control visual comfort. Second, indirect fluorescent lighting fixtures have been introduced such that the lamp does not directly face workers under the fixtures. While such indirect lighting fixtures are generally pleasant, the design of the indirect fluorescent luminaires optics often does not account for the ceiling reflective properties, thus delivering reduced light levels at the work surface.
Elements and steps in the figures are illustrated for simplicity and clarity and have not necessarily been rendered according to any particular sequence or scale. For example, steps that may be performed concurrently or in different order are illustrated in the figures to help to improve understanding of embodiments of the present invention.